Yan Su turned around and noticed that Zhen Ai's complexion had improved significantly; her face was still a bit flushed. Just as he was about to ask her something, she immediately withdrew her hand and murmured, "I'm sorry, I got your hand dirty."
It was only then that Yan Su realized her hand was covered in sticky blood, and he had some bloodstains on his own hand as well.
He glanced at the grass and then took her over to the sprinkler nearby to wash her hands.
He quickly cleaned his hands, but the blood on her hands had already clotted.
After all, it was human blood, and she couldn't help but feel anxious, rubbing and picking at her hands until they were a deep crimson. Yan Su frowned and pulled a handkerchief from his pocket, taking her hand without giving her a chance to protest and began wiping it for her.
Zhen Ai tried to pull away again, but once more, she couldn't resist his strength.
"Don't move!" he commanded in a low voice.
As he said this, he didn't lift his head but meticulously wiped her palms, backs of her hands, and even between her fingers and under her nails.
Zhen Ai froze, staring at his lowered brows and eyes. He was so serious, and his movements were so gentle and meticulous, as if he were handling his most cherished books.
The soft material of the handkerchief, mixed with the cool water, and the warmth of his palm gathered in Zhen Ai's hands, creating a tingling sensation. The coolness slowly spread to her heart, intensifying the tingling.
From childhood to now, no one had ever washed her hands for her, not even her mother. Back then, her mother would stand by the sink, holding her hands, watching little Zhen Ai tiptoe on a stool, scrubbing her tiny hands under the faucet.
She absentmindedly said, "When I washed my hands before, my mom would stand beside me and say, 'You need to wash for 21 seconds.'"
Yan Su didn't lift his head: "Your hands are too dirty; you need to wash for more than a dozen 21 seconds."
Zhen Ai fell silent, lost in thought.
Once, she had seen Tyler wash Jiang Xin's hands at school; he had hugged her from behind, his light bronze hands affectionately scrubbing Jiang Xin's delicate white hands under the clear water. They giggled together, and the water droplets sparkled in the sunlight, looking beautiful.
At that time, she had inexplicably thought that since Tyler often played basketball, his hands must be calloused and rough, yet full of texture—just the kind of lively boy she admired.
And now, on the verdant lawn, as the delicate water flowed down, the hands intertwined with Zhen Ai's were white and slender, with well-defined knuckles yet firm.
Zhen Ai stared blankly at how he cradled her hand in his palm, carefully wiping away the mottled bloodstains from between her fingers, their index fingers overlapping...
Her face gradually grew hotter.
But just like him, his actions were still clean, without any flirtation, purely caring and affectionate.
Her racing heart gradually calmed down.
It seemed he always had a way of soothing others.
Zhen Ai steadied her heart and asked, "How did you create that sketch of the bomb thrower?"
"Part of it is based on the work of predecessors," he said sincerely, without any hint of taking all the credit or seeking praise.
"Types such as the mentally ill, sadists, those with PTSD, arsonists, and bomb throwers have all been sketched out based on the experiences of predecessors."
"Is that so?" Zhen Ai's curiosity piqued. "So, the police system has general sketches for different types of criminals, like serial killers?"
"Yep. The FBI proposed a classification method in the 1980s: organized serial killers and disorganized serial killers."
Zhen Ai speculated, "So the mentally ill fall into the disorganized category?"
Yan Su was gently rubbing away a clotted piece of blood from her hand with his thumb: "In addition to the mentally ill, there are also murderers with severe PTSD. Both of these categories lack organization.
Because their reasoning and social functions are relatively dull, it's easier to assess crime scenes—
They act impulsively, don't deliberately choose victims, don't come with tools, and they don't clean up the scene after committing the crime."
"What about organized criminals?" Zhen Ai asked. "Like arsonists, isn't it difficult to collect evidence from a fire?"
Yan Su replied effortlessly, "In the U.S., 94% of arsonists are male, 75% are white, and they are usually young, aged between 17 and 27. They often wet the bed as children, struggle with relationships, and have low self-esteem. Their methods escalate, and arsonists ultimately tend to evolve into serial killers."
Zhen Ai fell silent.
Just as Yan Su said, behind each of these data points was the result of countless police officers and sketch artists accumulating knowledge, gradually outlining the profile of criminals over the years.
Thinking about it this way, it represented the gathering and condensation of generations of justice!
Those who uphold justice have never walked alone!
Zhen Ai felt a warm surge of strength in her heart and returned to the topic: "So, what about the bomb thrower?"
Yan Su was still focused, gently cleaning the fine spaces under Zhen Ai's nails. Zhen Ai felt a tickling sensation in her fingertips and flinched slightly, but once again, he held her hand firmly.
After a while, he said, "Bomb throwers are generally driven by three motivations: terrorism, political objectives, and personal grievances."
Zhen Ai thought carefully, "Terrorist attacks would target crowded places like subways or Times Square. As for political motives, they'd be better off targeting government buildings or military facilities."
"Smart," Yan Su said, his lips curving into a slight smile. "I really like people who think for themselves, even if it's just a fleeting moment of brilliance."
Zhen Ai: …
She asked, "Are there also statistics on bomb throwers?"
"Yeah, the FBI's profile of bomb throwers indicates that—98% are male, socially isolated, and have a history of willful destruction. About 50% of bomb throwers injure themselves in the process, and a portion even die while planting the bombs."
Zhen Ai felt a wave of frustration: "What a thankless and foolish endeavor for humans!"
Yan Su laughed at that, then added, "On the contrary, bomb makers are usually quite intelligent. Of course, that doesn't include those who haphazardly mix graphite and sulfur and end up blowing themselves up."
After the joke, he continued the previous topic: "Bomb throwers driven by personal grievances aim to vent their anger and commit murder; the bomb is just their tool. Therefore, they will choose their targets with precision. Thus, the location and the crowd involved reveal their grievances and identity."
Yan Su glanced at the chaos in the area of the explosion on campus. "He has lived in this environment for a long time but has always been overlooked by the people here. The explosion is an outburst of his emotions and a way to draw attention. At that moment,
he was telling the people on this campus: 'Look at me, I'm making a grand entrance!'"
Zhen Ai's heart trembled slightly. How twisted must that person's psyche be to feel the need to prove his existence in such a manner?
"So, you believe the bomb thrower is a student or staff member at this school. Then… was this bomb randomly targeting people?"
"No. Among those who ignore him, there must be one or a few who particularly trigger his nerves." Yan Su held her damp little hand and suddenly felt how soft and boneless it was, more delicate than his parrot, and even more so than Mozart and Elvis.
He steadied his thoughts and briefly said, "This is the first bomb he has deployed; he needs to experiment and divert the police's attention."
Zhen Ai furrowed her brow as she realized:
"It's not just an emotional outburst; it's a meticulously planned murder.
Indiscriminate killing is, of course, safer than targeting a specific enemy and keeps him farther from the police's gaze. After a series of bombings, among countless victims, there will always be those he truly wants to kill. By then, how would the police know who his real target is? Without identifying the true target, it's hard to find the real killer."
Yan Su's lips curved slightly; she was adorably clever.
She finished speaking and suddenly smiled, "Good thing I have you; you can definitely stop him, right?"
Yan Su, lost in thought about other matters, felt his face stiffen at her trust and flattery. He mumbled a vague "mm" and silently decided to wash her hand again.
Zhen Ai was fully engaged in the reasoning, unaware that her hands were already clean. She continued to ask, "So, does his organized approach and perfectionism come from the bomb's construction?"
"Yep, that bomb is quite refined for an ordinary bomb maker. He even used a mercury switch; he's imaginative and creative, treating his work like art."
Zhen Ai thought to herself, anyone who could treat a murder weapon as art was indeed twisted and terrifying. Such a person shouldn't be allowed to linger: "How do you know the suspect is in your photo?"
"Bombs are highly lethal and destructive weapons, a combination of intellect and supernatural power. The more dangerous the process, the more extraordinary the recognition and satisfaction the creator feels at the moment of detonation. After hundreds or thousands of hours dancing with danger, would he abandon the one moment it serves its purpose?"
Zhen Ai nodded in understanding: "So he would wait at the scene to see the explosion!"
This made Yan Su pause; he had overlooked a detail!
He immediately pulled out his phone, ignoring that his hands were wet, and called Blake: "We've narrowed down the suspect. He's likely at a cultural booth on that street, allowing him to monitor the bomb on the stairs without raising suspicion."
After quickly finishing his call, he turned and hugged Zhen Ai, exclaiming, "Smart girl!"
Zhen Ai was suddenly embraced, feeling his broad, sturdy frame filled with the scent of a man, almost making her heart race, but it was only for a fleeting moment.
She smiled shyly, happy to be of help.
"Actually, there's another possibility," Yan Su released her and mused aloud, "It could be those doctors or police officers who want to satisfy their heroism by playing the savior role, but considering 1. they don't have enough independent time, 2. the amount of explosives is too great, we can rule that out."
"Yeah, if it's a police officer, they'd just shoot directly; if it's a doctor, they'd rather infect people…" Zhen Ai's heart jolted at this thought, and she quickly shut her mouth.
After a while, she cautiously glanced at Yan Su, but he seemed unfazed, instead turning off the faucet, wringing out the handkerchief, and carefully drying her hands.
The two then stood up to look at the surveillance footage.
Just then, the bomb disposal expert from the police station was about to leave with the bomb fragments when Yan Su squinted and shouted, "Wait!"
He picked up a piece of debris from the expert's hand and, after examining it, asked, "What's this scratch in the middle?"
The expert glanced at it: "That's not from the explosion; it should be a mark left by the creator. Generally, bomb makers treat their bombs as artworks and will leave their unique symbols inside. But these are usually very simple and don't convey any specific information."
Yan Su raised an eyebrow, asking, "What symbol can be pieced together from the fragments?"
The expert replied, "It should form a triangle with a straight line at the top."
Yan Su pondered for a moment, then strode forward, gesturing for Zhen Ai to follow as he dialed his phone: "Officer Blake, the bomb thrower is likely wearing white today."
When he hung up, Zhen Ai pressed, "Why do you think he might wear white today?"
Yan Su walked quickly: "The triangle has a straight line at the top; what does that shape look like when flipped upside down?"
Zhen Ai recalled Yan Su's lecture from a few hours ago and exclaimed, "That looks like a cup!"
"Smart." Yan Su smiled subtly, clearly pleased that she paid attention during his lecture. "That's the shape of the Holy Grail."
"You mean he's religious?"
"Not necessarily, but at the very least, he's familiar with the doctrines and stories, and he likely adheres to some unspoken rules given his silent, severe, and quirky nature."
"That rule…" Zhen Ai's mind lit up, "After Labor Day in September, you don't wear white?"
Yan Su glanced at her sideways, silent but approving.
With autumn approaching, wearing white was discouraged.
And now,
Zhen Ai looked at the new greenery by the roadside: "It's the beginning of spring."